Our Research on the Inclusion of Labor into Supply Chain Networks

On this Labor Day, September 6, 2021, I thought it appropriate to write this blogpost in celebration of labor in the pandemic. Indeed, the COVID-19 pandemic has vividly and dramatically shown the importance of keeping our workers healthy and safe in all sectors of the economy from agriculture to healthcare. Many worked tirelessly and some suffered tremendously to ensure that products were produced, transported, and then consumed. Essential workers have become our heroes from farmers and food processors to freight service providers, including truckers, to healthcare workers, educators, and many others. 

During the pandemic, I have been researching how to include labor into supply chain networks so that disruptions could be better quantified, appropriate wages identified, and, even more recently, how firms should invest in enhancing the productivity of their workers through enhanced health and safety measures. This research continues and has become a great passion of mine.

I am pleased that three papers of mine on the inclusion of labor have now been published. The first paper, "Perishable Food Supply Chain Networks with Labor in the Covid-19 Pandemic," was published in the edited volume: Dynamics of Disasters - Impact, Risk, Resilience, and Solutions, I.S. Kotsireas, A. Nagurney, P.M. Pardalos, and A. Tsokas, Editors, Springer Nature Switzerland AG, 2021,  pp. 173-193. A prepint of it can be downloaded here.

The second paper, "Optimization of Supply Chain Networks with Inclusion of Labor: Applications to Covid-19 Pandemic Disruptions (2021),  was published in the International Journal of Production Economics, 235, 108080.

This IJPE paper continues to be among the most downloaded from the journal website over the past couple of months, which demonstrates the interest in this topic. This paper focused on the healthcare product supply chains, including PPEs.

The above two papers are optimization models and capture different types of constraints on labor availability. 

My paper, "Supply Chain Game Theory Network Modeling Under Labor Constraints: Applications to the Covid- 19 Pandemic (2021), was published in the European Journal of Operational Research, 293(3), 880-891. It proposes a series of game theory models in which competition for labor by firms is also considered. This is something that we are seeing in the COVID-19 pandemic, which has different sectors suffering from labor shortages. 

I was greatly honored that the Editors of this journal selected this paper of mine for an Editors' Choice Award and the publisher has made the paper available for free from the journal website.

I have also spoken at multiple conferences about this research; most recently, at the MOPTA Conference organized by Lehigh University, which I enjoyed very much. The title of my plenary talk at MOPTA was: "Labor and Supply Chain Networks: Insights from Models Inspired by the COVID-19 Pandemic."

The full slide deck of  my plenary talk can be downloaded here.

The above papers all acknowledge and thank essential workers. And, today, I extend my gratitude to laborers world-wide. 

Decision-Making Under Deep Uncertainty With Applications to Energy

I arrived back from Washington DC about 1AM this morning after a late flight. I was in DC to speak and take part in a fascinating international expert panel on Financial Supernetworks.

Today, I had a lot to catch up on but was very much looking forward to hearing my College of Engineering colleague, Professor Erin Baker, speak this afternoon in our UMass Amherst INFORMS Speaker Series. Her presentation title is below.

This Speaker Series is organized by the award-winning UMass Amherst INFORMS Student Chapter.

The students had brought food - pizza plus pastries and fresh fruit and rinks, which were served prior to Professor Baker's lecture. She was introduced by the very energetic and hard-working Chapter President, doctoral student in Management Science at the Isenberg School, Pritha Dutta.

Professor Baker's outstanding talk presented a theoretical framework to handle "deep uncertainty," as when experts are in conflict or models are in conflict. She focused in her talk on the former. The very elegant theoretical framework consisting of alternatives, uncertainty, and preferences, along with expert beliefs used in a Bayesian way provide us what she and her collaborators are calling "belief dominance" in contrast to stochastic dominance and Pareto dominance. The framework eliminates bad solutions and from the set of the best ones identifies the robust ones.

Her research focuses on decision analysis and energy, including renewables (and she is head of a big NSF IGERT project on wind energy). She is an active member of INFORMS.

The application of the theoretical framework was to energy R&D portfolios since there is disagreement among experts on the best solutions for climate change.

Part of the motivation for the research that she presented today was that dynamic decision-making under uncertainty and learning has been criticized as lacking external consistency. It does make a lot of sense that in robust decision-making (and multiple stakeholders) one should start with a small number of alternatives and share with the stakeholders.  Stakeholders appreciate transparency. Her application to a portfolio of energy investment choices, such as nuclear, biomass, etc., at 3 different levels, was vividly illustrated in different colors highlighting belief dominance.

There was an excellent Q&A that followed after Professor Baker's talk and I snapped the group photo below).

Many thanks to Professor Baker for speaking today especially since you had even taught a class shortly before!

Brilliant Lecture by Chief Technologist Dr. Eugene Litvinov of ISO New England

Today we had the honor and privilege of hosting Dr. Eugene Litvinov, who is the Chief Technologist at the Independent System Operator (ISO) New England. Dr. Litvinov spoke in our UMass Amherst INFORMS Speaker Series, which is organized by the UMass Amherst INFORMS Student Chapter. The student chapter, some faculty, and I had the pleasure of touring ISO NE's facilities in Holyoke, MA  last spring and Dr. Litvinov was so fascinating that we were thrilled when he accepted our invitation to speak.

He attracted an audience from the Isenberg School of Management, the College of Engineering, and even folks from Physical Plant at UMass since we operate our own microgrid as well as other guests from the community. It was great to see so many PhD students and even MBA students in attendance on a Friday afternoon.

The title of his talk was "Challenges of the New Grid."

ISO NE ensures that the lights stay on in our region, that is, this organization ensures electric power reliability. It is also involved in wholesale trading as well as planning for electric power.

We began his visit with a delicious lunch at the University Club at UMass and were joined by Professor Erin Baker and two of her doctoral students. She is the PI on an NSF IGERT on wind energy. Also joining us was one of our PhD students from the Isenberg School.

The conversation at lunch was so interesting. We discussed issues of survivability, cybersecurity and the grid, renewable energy, internships, skillsets needed in this industry, and other topics and we made it to the seminar location jut in time.

The audience was eagerly awaiting Dr. Litvinov'a presentation.

I started the introductions and then our new Student Chapter President, Zana Cranmer, completed the welcome. We also noted that the student chapter last week at our INFORMS conference in Philadelphia had received the summa cum laude award from INFORMS. We had chocolate cake (to be eaten after the talk) and our award plaque displayed.

Dr. Litvinov mentioned how the grid consists of the eastern interconnection, the western interconnetcion, and that Texas is its own country.

He noted that ISO NE manages $11 billion in energy capacity a year, which is mind-boggling. Every second the monitoring of supply and demand of electricity takes place since electric power cannot be stored.

New challenges for our region include that a big percentage of the fuel is now natural gas and we don't have sufficient pipeline capacity to transport it (our region does not produce natural gas). This winter could be interesting, to say the least.

He noted that we now need different ways of controlling the system since it is much more decentralized than it has ever been. He spoke of offering customers different levels of reliabilty, which I found quite interesting.

He also noted that the transmission architecture is a mesh and the distribution architecture of the grid is radial. He emphasized the need for greater flexibility. I very much appreciated his emphasis on the importance of definitions whether they are for flexibility, reliability, survivability,  or even resilience. He spoke about risk-based optimization, which I thought was very cool, and noted robust optimization several times in his talk. I might add that Litvinov has collaborated with Dimitri Bertsimas of MIT Bertsimas spoke in our series a few years ago, as did his wife, Georgia Perakis, who had the same advisor at Brown University as I did (Stella Dafermos).  so I guess Bertsimas is my academic brother-in-law.

Dr. Litvinov  emphasized the importance of keeping the system in balance and to manage the uncertainty. I liked him saying that one needs to determine the largest set of uncertainty that can be handled without violating constraints and said that he has a paper on this, which I definitely want to read.

Dr. Litvinov also discussed that we are moving from coordinated control of the grid to cooperative control (hopefully) along with decentralized decision-making. He had visited Paris recently and viewed how electric power is managed there.

He  presented quite a few mathematical optimization models so it was great for the students to see how important mathematical programming and optimization are in this critical infrastructure sector.

His lecture was brilliant and so impressive.

The questions that followed demonstrated the interest of those who attended. There were questions on renewable energy, what his vision for the grid would be for 2030, and even cybersecurity (a growing group at ISO NE).

Dr. Litvinov stayed to answer more questions and was very generous with his time and, given his reponsibilities, we are truly grateful for his visit and his talk.

And then it was time to indulge in a piece of delicious cake from Whole Foods. What a great Friday afternoon and what a terrific day, which started with meetings in Computer Science this morning.